As Facebook’s stock tumbled after hours on concerns about Facebook’s slowing growth, CEO Mark Zuckerberg, COO Sheryl Sandberg and CFO David Ebersman hosted an investor call in which they stressed the potential of mobile and social ads.

One particularly compelling tidbit: The company is selling $1 million in its new ad format “Sponsored Stories” every day, and over half of that is mobile.

Zuckerberg kicked off the call by focusing on mobile—saying that’s where they’re “investing heavily” because of massive potential. People who access Facebook on their mobile devices are 20 percent more likely to access it on a given day. But for now, that shift to mobile is a problem—and responsible for slowing growth—since they’re just starting to display mobile ads.

And as committed as Zuckerberg is in distributing ads to users mobile phones, he says “it wouldn’t make sense” for the company to “build out a whole phone.”

The other big message: social ads, like “Sponsored Stories” work. Sandberg says the new format performs multiple times better than display ads, and the company’s making changes to roll them out broadly. Right now fewer than half of Facebook’s ads are social, Sandberg says.

Facebook Must Focus On Mobile: Expert

"The key for Facebook is mobile, mobile is a big big trend with over half their users using mobile devices and they need to look at ways to maximise profitability of add revenue through mobile devices," Paul Hawtin, CEO and founder at Derwent Capital, told CNBC.

According to Sandberg the potential to improve the quality of ads and increase their market is huge. The new “Facebook Exchange” aims to increase the relevance of ads users see on Facebook. Local ads, Sandberg says, are “the holy grail of the internet,” but the problem is that small businesses are “not very tech savvy.” Facebook’s familiar interface, she says, is just the way to get them online and paying to reach customers.

What drove the company’s costs higher costs? The combination of payroll tax and restricted stock units totaled $1.3 billion, instead of the $965 million earlier estimated. Headcount grew nearly 50 percent in the last year. And Ebersman says the company is investing $1.3 billion to $1.6 billion in capital expenditures on leases and equipment.

When pushed on the company’s plans for video and commerce, Facebook’s team revealed a willingness to go into these new, potentially lucrative areas. Zuckerberg said “overtime more and more nuanced experiences will become social. Media stuff requires more nuance, commerce will require more. We’ll build out the tools to enable those products and be able to capture a percentage of that revenue.”

But from investors perspective, none of these big plans are happening quite fast enough.